Technical Field
Embodiments described herein are related to power management in integrated circuits.
Description of the Related Art
Integrated circuits are often included in various mobile devices, which are frequently operated on a limited power source such as a battery. In other cases, integrated circuits may be incorporated into devices with limited ability to remove thermal energy (heat). In devices like these, conserving power is a key design feature for the integrated circuits.
Digital integrated circuits include one or more clocks to control transitions in the integrated circuit, to cause storage devices such as latches, flops, registers, memory arrays, etc. to capture and launch data, etc. Distributing the clock over the semiconductor area occupied by the integrated circuit is challenging. At the high clock frequencies employed within many integrated circuits, the clock tree needs to be as balanced as possible, matching line lengths, loads, and delays from the clock source to the receiving circuitry. Fanout and load of the clock signals, and similarity of the buffering chains, is managed closely. If these parameters are not carefully managed, clock skew and jitter may be high, reducing the performance of the integrated circuit. These factors tend to lead to large and complex clock propagation networks, or clock trees, which consume a significant amount of power. The power consumption is significant both because of the size and load of the clock tree, but also because the clock is toggling every clock cycle during operation. In some cases, clock power may be as much as 50% or more of the overall power consumption in an integrated circuit.